How we measure internet censorship.

Vantages

37+ probe nodes are deployed across 200 countries on six continents. Vantage selection balances three constraints: presence inside affected jurisdictions, ASN diversity (so a single ISP outage doesn't fake a censorship event), and operator safety. We do not run probes from infrastructure that exposes operator identity.

Test list

80 domains spanning news, civil-society organizations, encrypted messaging, circumvention tools, social platforms, and reference content. The list is reviewed quarterly and additions are governed by the same anti-targeting rules used by OONI's test list.

Cadence

Every probe runs the full domain list every 5 minutes, 24×7. That gives a worst-case detection latency around 5 minutes for a sudden block, and a 1-hour rolling baseline sufficient to flag throttling that ramps up gradually.

Anomaly classifier

• DNS tampering. Resolver returns an IP that doesn't match the known ASN, returns NXDOMAIN, or refuses recursion.
• TLS interference. Handshake interrupted at SNI, certificate altered, ClientHello rewritten.
• HTTP blocking. Block page returned, content rewritten, response throttled to zero.
• BGP withdrawal. Origin AS disappears from the global routing table for the target prefix.
• Throttling. Bandwidth deliberately collapsed for specific services while neighboring services remain unaffected.

Cross-source verification

An anomaly is only promoted to a verified incident after it correlates against at least one independent measurement project for the same target, location, and time window:

• · OONI — Open Observatory of Network Interference (community probe network)
• · CensoredPlanet — University of Michigan
• · IODA — Internet Outage Detection and Analysis (Georgia Tech)

Confidence levels

Anomaly

Single probe, single source. Surface as "observed" only.

Corroborated

Multiple Voidly probes, OR one external project agrees. Public dataset, with caveat.

Verified incident

Voidly + ≥1 external source agree. Citable, included in counters and forecasts.

Forecasting

7-day shutdown forecasts are produced from a model trained on 10 years of historical measurements, conditioned on country-level political and security signals. Forecast quality varies by region; per-country reliability is published alongside the forecast.

Reproducibility

The full measurement dataset (CC BY 4.0) is downloadable from the HuggingFace datasets listing or queryable via the Voidly REST API. The classifier code is published in the voidly-ai GitHub org; anyone with a probe can reproduce a measurement and submit independent corroboration.